1. Field of the Invention
This invention relates to an organic photoconductive material for electrophotography which is used as an electrophotographic material or a photoconductive toner.
2. Description of the Prior Art
An electrophotographic material is a practical device in which an organic photoconductive compound is used.
Polymeric photoconductive compounds such as polyvinylcarbazole (PVCz) and low-molecular-weight photoconductive compounds such as hydrazone derivatives have been widely known as organic photoconductive compounds for use in the electrophotographic material. Since the photoconductive polymers do not show conductivity to visible light and the low-molecular-weight photoconductive compounds do not generate carriers under visible light, they cannot be used alone in the electrophotographic material, but must be sensitized to a visible light region by combining them with electric charge-generating pigments.
Accordingly, in the production of electrophotographic materials, it is necessary to disperse a charge-generating pigment in a binder polymer. Pigments are generally insoluble in solvents, and are extremely difficult to disperse uniformly in binder polymers. Even when uniform dispersion can be effected, the stability of the resulting dispersion is not satisfactory. Furthermore, since pigments are flocculated particles, variations in pigment manufacturing conditions greatly affect the electrophotographic properties of the resulting electrophotographic material. The properties of pigments must therefore be controlled in order to eliminate such an adverse effect.